Troubleshooting Procedure - Tektronix 213 DMM Instruction Manual

DIAGRAMS. Complete circuit diagrams are on the foldout
pages in the Diagrams section at the rear of this manual. The
circuit number and electrical value of each part is shown on
the diagrams (see the first page of the Diagrams section for
the definition of the reference designators used to identify
parts). Important voltages and waveforms are shown on
the diagrams. The portions of the circuits mounted on cir-
cuit boards are enclosed with blue lines.
CIRCUIT BOARDS. Figure 4-2 shows the location of the
circuit boards within the instrument along with their assem-
bly (A) numbers. The assembly numbers are also used on
the diagrams to aid in locating the boards. To aid in cross-
referencing between the diagrams and the circuit board, cir-
cuit board layouts are shown in the Diagrams section oppo-
site the circuit diagram. Each electrical component on the
boards is identified by its circuit number and listed in the
table near the circuit board layouts. To find a component,
locate it in the component list and note the coordinates
listed with it. Then locate the coordinates on the layout
and the component is located within this area.
SEMICONDUCTOR LEAD CONFIGURATION. Figure
9-1 shows the lead configurations of the semiconductors
used in this instrument. The cathode end of most diodes
used in this instrument are indicated by a stripe, a series of
stripes, or a dot.
COMPONENT AND WIRING COLOR CODE. Colored
strips or dots on resistors and capacitors signify electrical
values, tolerances, etc., according to EIA standard color
c0de. Components not color-coded usually have the value
printed on the body.
Except for the crt three-connector terminal connector hol-
der, terminal connector holder wiring is also color-coded to
each numbered connector according to the EIA color code
(e.g., pin 2 has a red striped wire, pin 3 an orange striped
wire, pin 6 a blue striped wire, etc.).
The E IA color code as used for some parts is shown in
Figure 4-12.
Troubleshooting Procedure
The following troubleshooting procedure is arranged to
check the simple trouble possibilities before proceeding
with extensive troubleshooting. The first few checks insure
proper connection, operation, and calibration. If the trou-
ble is not located by these checks, the remaining steps aid
in locating the defective component or part.
1. Check Control Settings. Incorrect control settings can
indicate a trouble that does not exist. If there is any ques-
@
Maintenance-213 Service
tion about the correct function or operation of any control,
refer to the Operating Instructions section.
2. Check Associated Equipment. Before proceeding with
troubleshooting check that the signal is properly connected
and that the interconnecting cables are not defective.
3. Visual Check. Visually check the portion of the instru-
ment in which the trouble is located. Many troubles can be
located by visual indications such as unsoldered connections,
broken wires, damaged circuit boards, damaged components,
and interconnecting pins not inserted into their respective
sockets.
NOTE
The spring tension of the pin sockets ensures a
good connection between the circuit board and
the pin. This spring tension can be destroyed
by using the pin sockets as a connecting point
for spring-loaded probe tips, alligator clips, etc.
4. Check Instrument Performance. Check the_ operation of
the unit, or the affected circuit by performing the Perfor-
mance Check procedure of Section 5. The apparent trou-
ble may only be a result of misadjustment and may be cor-
rected by calibration. Complete calibration instructions
are given in Section 6.
NOTE
At this point in the procedure it is recommended
that the AID Converter Board and Power Supply
Board extender cards be installed (see Trouble-
shooting Aids for installation instructions).
5. Isolate Trouble to a Circuit. To isolate trouble to a par-
ticular circuit, note the trouble symptom. The symptom
often identifies the circuit in which the trouble is located.
(e.g., poor focus.indicates the crt circuit may be at fault).
Incorrect operation of all circuits often indicates trouble in
the power supplies. Table 4-1 provides the operating toler-
ances for the power supplies in the 213.
Figure 9-24 provides a guide for locating a defective circuit,
component, or part. When a defective circuit or component
is identified, proceed with steps 6 and 7 to locate the defec-
tive part(s).
NOTE
To better insure operator and equipment safety,
it is recommended that all troubleshooting be
done with the instrument operating on batteries,
unless there is a problem in the battery charger.
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